A display panel of the type known as a PANAPLEX panel comprises a gas-filled envelope containing groups of cathode electrode segments, each of which is adapted to display a character, and each of which is associated with an anode electrode. The anode electrode preferably comprises a thin film of tin oxide formed on the panel face plate. In one method of manufacturing such a panel, the face plates are purchased with the anode patterns already formed. Such face plates are relatively expensive. The present invention provides an inexpensive etchant and simple method of etching tin oxide films.